1. Field of the Invention
The present invention relates to a method and apparatus for compensating an attitude of an inertial navigation system and a method and apparatus for calculating a position of the inertial navigation system using the same.
2. Description of the Related Art
In order to measure a position and an attitude of an object that moves in a three dimensional space using an inertial sensor, an inertial measurement unit comprising a triaxial acceleration sensor and a triaxial angular velocity sensor should be used. The attitude of the inertial navigation system can be obtained by solving a differential equation for the angular velocity measured by a gyroscope used as the triaxial angular velocity sensor. The position of the inertial navigation system can be obtained by removing a gravity component according to the attitude of the inertial navigation system and from the acceleration measured by an acceleration sensor and by a double integral of the acceleration from which the gravity component is removed. In this case, due to the gyroscope's drift and other noise, the attitude error of the inertial navigation system increases over time for the angular velocity error, and the error of the acceleration from which the gravity component is removed also increases over time for the angular velocity error. Thus, the position error of the inertial navigation system increases over a square of time for the acceleration error, and the attitude error of the inertial navigation system increases over a cube of time for the angular velocity error. Due to an error that rapidly increases in time, it is very difficult to calculate the position of the inertial navigation system using an inertial sensor for a long period of time. Thus, it is required to compensate the attitude of a moving object calculated from acceleration and angular velocity measured by inertial sensors and to calculate the position of the object.